Efficient Long-Range Triplet Exciton Transport by Metal-Metal Interaction at Room Temperature.

Efficient and long-range exciton transport is critical for photosynthesis and opto-electronic devices, and for triplet-harvesting materials, triplet exciton diffusion length ( ) and coefficient ( ) are key parameters in determining their performances. Herein, we observed that Pt and Pd organometallic nanowires exhibit long-range anisotropic triplet exciton L of 5-7 μm along the M-M direction using direct photoluminescence (PL) imaging technique by low-power continuous wave (CW) laser excitation. At room temperature, via a combined triplet-triplet annihilation (TTA) analysis and spatial PL imaging, an efficient triplet exciton diffusion was observed for the Pt and Pd nanowires with extended close M-M contact, while is absent in nanowires without close M-M contact. Two-dimensional electronic spectroscopy (2DES) and calculations revealed a significant contribution of the delocalized [dσ*(M-M)→π*] excited state during the exciton diffusion modulated by the M-M distance.